Coaxial Coupling

ABSTRACT

A coaxial coupling comprising a female part and a male part which are couplable to each other is disclosed. The female part and the male part having an inner passage and a concentric outer passage, wherein the inner passage of the female part is fluidly connected to the inner passage of the male part and the outer passage of the female part is fluidly connected to the outer passage of the male part in the coupled state of the coupling, one of the parts further comprising a by-pass valve that guides the fluid flow internally from the inner passage to the outer passage thereof in a non-coupled state of the coupling, the other part comprising an activator for activating the by-pass valve during coupling of the two parts wherein the by-pass valve is adapted to guide the fluid flow from the inner passage of the one part to the inner passage of the other part during coupling of the two parts.

This invention relates to a coaxial coupling, i.e. a coupling having aconcentric configuration, and especially to a quick connect coaxialcoupling.

Similar couplings are known from various patents, such as U.S. Pat. No.6,179,001. They are designed to allow the quick connection ordisconnection of two separate fluid lines, transporting for instance agas or a liquid, with a minimum fluid spillage. These couplings aretypically used in double acting hydraulic systems where flexible lines(hoses) are applied to transfer the fluid from a driving element, suchas a hydraulic pump, to an operating element, such as a hydraulic tool.For double acting hydraulic operating elements, such as double actinghydraulic cylinders, at least two separate fluid lines are required totransport the fluid from the operating element (pump) to the cylinderwhilst at the same time the residual fluid present in the cylinder mustbe transported back to the operating element (pump) to achieve amovement of the piston in the hydraulic cylinder. A valve between thedriving element and the operating element is applied to direct the fluidflow through the lines and alter the direction of the fluid flow toachieve an opposite movement of the piston in the hydraulic cylinder.The fluid lines will both have to transport pressurized fluid dependingon the position of the valve.

From U.S. Pat. No. 6,179,001 a coaxial coupling having a concentricconfiguration is known comprising a male part connected to a first andthird conduit and a female part connected to a second and a fourthconduit for releasable mutual connection, each comprising a one pieceouter shell, connecting channels and an end face at an end thereof. Atleast portions of the connecting channels in both male and female partare concentric and the end faces of the elements of both parts arelocated in a single plane.

For certain specific applications, such as portable hydraulic rescueequipment where the double acting hydraulic system comprises a controlvalve on the operating element (tool) itself to control the directionsof the fluid flow into the cylinder ports, the coupling from U.S. Pat.No. 6,179,001 is not suitable. The operation and the sequence of theinternal valve parts in that coupling with the aim to connect the fluidchannels with each other is too complicated and can cause trappedpressure which is unwanted in the specific field of application. Nextthe design includes many different sliding or moving parts/bushings(eight in total), seals (eight in total) and springs (nine in total),all to be activated by the insertion of the coupling parts into eachother, resulting in relatively much friction thus making it almostimpossible to couple the parts by hand.

The object of the present invention is to obviate the above statedproblems.

This object is achieved in that one part (preferably the female part) ofthe coupling is attached to the driving element and provided with just aby-pass valve which is capable of directing the fluid flow from theinner pressure passage to the outer concentric return passage whilstthis one part and the other part (preferably the male part) are not yetcoupled together. Next the design is simplified only using less movingparts (four in total), less seals for the valve functions (five intotal) and less springs (five in total).

During the coupling different steps will cause different actions fromthe by-pass valve in the female part and more valves in the male part.

The object of the different steps and the related actions is to minimizethe required force for the coupling and to prevent unwanted pressurebuild-up in enclosed fluid chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 longitudinal sectional view of a female part of a couplingaccording to the invention connected to a coaxial hose assembly,

FIG. 2 longitudinal sectional view of the female part of FIG. 1connected to a connection block,

FIG. 3 longitudinal sectional view of a male part of a couplingaccording to the invention connected to a coaxial hose assembly,

FIG. 4 longitudinal sectional view of the male part of FIG. 3 connectedto a connection block,

FIG. 5 longitudinal sectional view of the female part and male part ofFIGS. 1 and 3 respectively, partially coupled,

FIG. 6 longitudinal sectional view of the female part and male part ofFIGS. 1 and 3 respectively, halfway coupled, and

FIG. 7 longitudinal sectional view of the female part and male part ofFIGS. 1 and 3 respectively, fully coupled.

BRIEF DESCRIPTION OF THE ABBREVIATIONS AND REFERENCE NUMBERS

-   S indicates the various types of sealing elements-   L.P. means Low Pressure and stands for the outer passage i.e. return    line-   H.P. means High Pressure and stands for the inner passage, i.e.    pressure line-   1 Female sleeve 14 Inner ferrule-   2 Valve stem 15 Outer ferrule-   3 By-pass valve 16 H.P. hose-   4 Ball sleeve 17 L.P. hose-   5 Female body 18 Ball stop-   6 Locking sleeve 19 Connection block-   7 Locking ball 20 Male body-   8 Ring 21 Male L.P. valve-   9 Torsion spring 22 Male sleeve-   10 Hose fitting 23 Male H.P. valve-   11 O-ring 24 Male adapter-   12 Hose adapter 25 Male L.P. fitting-   13 Lock pin 26 O-ring-   27 Connection Block-   28 Female adapter

DETAILED DESCRIPTION OF THE FIGURES AND PREFERRED EMBODIMENT

FIG. 1 shows a longitudinal sectional view of a preferred embodiment ofa uncoupled female part of a coaxial coupling, wherein the female partis connected to a coaxial hose assembly 16,17 by means of a torsion-freehigh pressure hose connector 12,13 and a threaded low pressure hosefitting 10 screwed onto female body 5. The fluid from the pressurepassage flows back to the container (tank) of the drive element (pump)as is shown with arrows due to the position of the by-pass valve 3.

FIG. 2 shows the same uncoupled female part mounted to a connectionblock 19 of a driving element (pump) without using any additional parts.

FIG. 3 shows a longitudinal sectional view of the uncoupled malecounterpart of the coupling wherein the male part is connected to acoaxial hose assembly 16,17 by means of a torsion-free high pressurehose connector 12,13 and a threaded low pressure hose fitting 25 screwedonto the male body 20. At point D a special concave form is provided toease insertion and provide a guidance when inserting the male part intothe female part. At point E the groove is shown that is part of thelocking mechanism when both parts are fully coupled.

FIG. 4 shows the same uncoupled male part connected to a connectionblock 27 of an operating element (tool).

FIG. 5 shows both female and male parts during step A. The male part isinserted partially into the female part. The female sleeve 1 of thefemale part pushes the male L.P valve 21 inwards. This connects theouter passages of both parts at point F. The male sleeve 22 in its turnpushes the by-pass valve 3 in the female part out of its seat (shown atG) allowing the fluid from the inner pressure passage to flow to boththe outer passage of the male part as well as to the outer returnpassage of the female part. Since both return passages are connectedtogether and also still connected to the inner pressure passage, nopressure is build-up in the coupling system.

FIG. 6 shows the same coupling halfway coupled at step B. The male partis inserted further into the female part. By-pass valve 3 has now openedthe fluid passage to the inner male passage. The outer return passagesare still connected with each other and also with the inner pressurepassage. All passages are connected to each other and again no pressureis build-up in the coupling system.

FIG. 7 shows the same parts now fully coupled as step C. The male parthas reached its final position. By-pass valve 3 is now in its other seatand has now closed off the fluid passage at point G, which means thatthe fluid flow from the inner passage will only flow into the male innerpassage. At the same time the outer return passages are still connectedtogether.

Since there is no fluid circulation in the operating element (tool) ofhydraulic rescue systems whilst not coupled, the male part attached tosuch an operating element (tool) does not require an integral by-passvalve. This principle allows the design of a less complicated and muchmore compact coaxial coupling and coupling system.

According to the preferred embodiment the female part is always attachedto the outgoing line connection from the driving element (pump) and themale counterpart of the quick-connect coupling is always attached to theincoming line connections from the operating element (hydraulic tool,such as a spreader or cylinder).

Flexible conduits (hoses) of a variety of lengths with a female partmounted at one end and a male part at the other end will provide theconnection between the driving element (pump) and the operating element(tool).

Preferably in the case of portable double acting hydraulic rescueequipment, the inner concentric passage will be the pressure line,whereas the surrounding passage will form the return line, i.e. thenon-pressure return line to the fluid container (tank). This set up willprovide many advantages for the system compared to prior art couplingsystems. Typically the cylinders in these double acting rescue tools usetheir main force when the piston is advanced which results in largesurface area ratios. Ratios of 3,5:1 are not uncommon which means that3,5 times more fluid is returned to the fluid container (tank) when apiston of these cylinders is retracted. A coaxial coupling system with acompact inner pressure passage and a larger size outside return passageautomatically offers these fluid capacity advantages with the leastdimensional effects.

Next a coaxial coupling system offers more safety for the users. In caseof a pressure line failure, fluid spillage and/or hazardous fluidejection is prevented through the surrounding outside return line.

Portable double acting hydraulic rescue equipment is used with variouslengths of connection lines (hoses). Prior art couplings, without anintegrated by-pass valve, attached to the two separate flexible conduits(hoses), require users to return to the driving element (pump) to stopthe flow of fluid by means of a valve at the driving element (pump)prior to be able to disconnect such prior art coupling from an operatingelement (tool) in order to connect another operating element (tool).This action is time consuming and neglecting the proper procedure willdefinitely result in damaged equipment and/or inoperative equipment.When lives are at stake, this is not acceptable.

Using the coaxial coupling and coupling system according to theinvention, there is no need to switch a valve at the driving element(pump) in order to stop the fluid flow through the system. This meansthat the user can quickly disconnect one operating element (tool) andconnect another operating element (tool) without the need to return tothe driving element to deactivate and reactivate the fluid flow throughthe system.

According to the preferred embodiment both the female and male parts arefurthermore provided with an adapter 28 resp. 24 to allow the fixationto a body i.e. a connection block 19, 27 at a driving or operatingelement, or to a flexible conduit such as a coaxial hose assembly 16,17without the need of additional parts. The typical adapter connection isrequired to provide a torsion-free mounting of the threaded socket ofthe outer L.P. hose 17. The adapter 28,24 is locked in position on thehose adapter 12 by means of two radial lock pins 13. The lock pins 13can be connected to each other into a substantially U-shaped element.

1. Coaxial coupling comprising a female part and a male part which arecouplable to each other, the female part and the male part each havingan inner passage and a concentric outer passage, wherein the innerpassage of the female part is fluidly connected to the inner passage ofthe male part and the outer passage of the female part is fluidlyconnected to the outer passage of the male part in the coupled state ofthe coupling, one of the parts further comprising a by-pass valve thatguides the fluid flow internally from the inner passage to the outerpassage thereof in a non-coupled state of the coupling, the other partcomprising an activator for activating the by-pass valve during couplingof the two parts, characterized in that the by-pass valve is adapted toguide the fluid flow from the inner passage of the one part to the innerpassage of the other part during coupling of the two parts.
 2. Coaxialcoupling as claimed in claim 1, further comprising a by-pass channelprovided between the inner passage and the outer passage in the one partand two seats at both sides of the by-pass channel, wherein theactivator moves the by-pass valve from the first to the second seatduring coupling of the two parts.
 3. Coaxial coupling as claimed inclaim 1, wherein the one part is connectable via a coaxial hose assemblyconsisting of an inner hose and a concentric outer hose to a drivingelement, such as a pump.
 4. Coaxial coupling as claimed in claim 1,wherein the other part is connectable via a coaxial hose assemblyconsisting of an inner hose and a concentric outer hose to a hydraulicoperating element, such as a hydraulic rescue tool.
 5. Coaxial couplingas claimed in claim 1, wherein the one part is the female part. 6.Coaxial coupling as claimed in claim 1, wherein the female part and/orthe male part comprises an inner hose connecting element, a concentricouter hose connecting element and rotational connecting means forconnecting the inner hose connecting element to the inner hose of thecoaxial hose assembly.
 7. Coaxial coupling as claimed in claim 6,wherein the outer hose connecting element comprises a threaded part forconnection with the outer hose of the coaxial hose assembly.
 8. Coaxialcoupling as claimed in claim 1, wherein the outer surface of the femaleand/or male part is provided with a groove to hold an O-ring.
 9. Coaxialcoupling as claimed in claim 1, wherein the male part has a tapered orconcave cylindrical outer shape.